Venting and filtration systems with gas permeable membrane

ABSTRACT

Embodiments of the invention provide venting and filtration systems with a membrane that is permeable to gas and substantially impermeable liquid. The systems can remove a gas from a liquid entrained with gas. The systems can include a reservoir in fluid communication with the membrane and a liquid outlet. The membrane can help prevent the gas from reaching the liquid outlet.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to U.S.Provisional Patent Application No. 61/109,859 filed on Oct. 30, 2008,the entire contents of which is incorporated herein by reference.

BACKGROUND

Air or other gases dissolved or otherwise trapped in liquids are knownto cause problems in liquid supply systems, such as mixing systems andfiltration systems. Entrapped gas can decrease the performance of thefiltration system. For example, air and other gases separated from theliquid within the filtration system can result in an uneven loading of afilter and can reduce a flow rate through the filtration system. In amixing system, entrapped gas may not only be undesirable, but can alsobe harmful to equipment in the mixing system. Thus, it is desirable toremove air and other gases from the liquid to reduce or minimize suchharmful effects.

Hydrocarbons, such as motor oils, automatic transmission fluids, andliquid food products, are a complex mixture of chemicals and additives.If a microporous membrane is used to remove a gas from a stream ofhydrocarbons, the various molecular sizes, surface tensions, and otherproperties of the chemicals and additives can result in clogging of thepores of the membrane and can result in some components of thehydrocarbons wetting and flowing through the membrane.

SUMMARY

Some embodiments of the invention provide a filtration system thatfilters liquids entrained with gas. The filtration system can include ahousing with a reservoir. A filter can be positioned in the reservoirand can divide the reservoir into an upstream chamber and a downstreamchamber. A non-porous membrane can be in fluid communication with theupstream chamber. The non-porous membrane can be permeable to gas inorder to vent gas from the reservoir. In some embodiments, the membranecan be porous or non-porous and can be permeable to the gas in order toallow the gas to flow from the upstream chamber to the downstreamchamber.

Some embodiments of the invention provide a venting system that ventsgas from liquid entrained with gas. The venting system can include ahousing with a reservoir. The reservoir can include a fluid inlet, a gasoutlet, and a liquid outlet. The venting system can also include anon-porous membrane in fluid communication with the reservoir and thegas outlet. The non-porous membrane can be permeable to the gas andsubstantially impermeable to the liquid. In some embodiments, themembrane can be porous or non-porous and a weir can be positioned withinthe reservoir. The weir can be in fluid communication with the fluidinlet.

DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional schematic view of a prior art filtrationdevice according to one embodiment of the invention.

FIG. 1B is a cross-sectional schematic view of a fluid flowing throughthe prior art filtration device of FIG. 1A.

FIG. 2A is a cross-sectional schematic view of a filtration devicecapable of venting a gas to an ambient environment according to oneembodiment of the invention.

FIG. 2B is a cross-sectional schematic view of a filtration devicecapable of venting a gas back into a fluid stream, while not allowingliquid to bypass the filtration device, according to one embodiment ofthe invention.

FIG. 3A is a cross-sectional schematic view of a venting systemaccording to one embodiment of the invention.

FIG. 3B is a cross-sectional schematic view of a venting systemaccording to another embodiment of the invention.

FIG. 4A is a cross-sectional schematic view of a venting systemaccording to one embodiment of the invention.

FIG. 4B is a cross-sectional schematic view of the venting system ofFIG. 4A including a baffle according to one embodiment of the invention.

FIG. 4C is a cross-sectional schematic view of the venting system ofFIG. 4A including a plurality of baffles according to one embodiment ofthe invention.

FIG. 5A is a cross-sectional schematic view of a venting systemincluding a weir having a substantially constant cross-sectional areaaccording to one embodiment of the invention.

FIG. 5B is a cross-sectional schematic view of a venting systemincluding a weir having a variable cross-sectional area according to oneembodiment of the invention.

FIG. 5C is a cross-sectional schematic view of a venting systemincluding a weir having a substantially constant cross-sectional areaupstream of a variable cross-sectional area according to one embodimentof the invention.

FIG. 5D is a cross-sectional schematic view of a venting systemincluding a weir having a substantially constant cross-sectional areadownstream of a variable cross-sectional area according to oneembodiment of the invention.

FIG. 6A is a cross-sectional schematic view of a venting systemincluding a weir having a curved inner wall according to one embodimentof the invention.

FIG. 6B is a cross-sectional schematic view of a venting systemincluding a weir having a curved inner wall and a curved outer wallaccording to one embodiment of the invention.

FIG. 7 is a perspective view of a venting system according to oneembodiment of the invention.

FIG. 8 is an exploded perspective view of the venting system of FIG. 7.

FIG. 9 is a perspective top view of an internal portion of a housing ofthe venting system of FIG. 7.

FIG. 10 is a perspective top view of the internal portion of the housingof FIG. 9 with a weir installed according to one embodiment of theinvention.

FIG. 11 is a cross-sectional view of a weir of the venting systemaccording to one embodiment of the invention.

FIG. 12 is a velocity vector plot of fluid flow paths through theventing system of FIG. 7.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass both direct and indirectmountings, connections, supports, and couplings. Further, “connected”and “coupled” are not restricted to physical or mechanical connectionsor couplings.

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

FIGS. 1A and 1B illustrate a prior art filter device 1 used infiltration applications. The filter device 1 can include a filterhousing 2 having an inlet 3 and an outlet 4. The filter housing 2 cansupport a filter 5. As shown in FIG. 1B, a fluid can enter the filterhousing 2 through the inlet 3, can flow through the filter 5, and canexit the outlet 4. The fluid can include a liquid 6 and a gas 7. As thefluid is introduced through the inlet 3, it begins to wet and permeatethe filter 5. Once the filter 5 becomes completely wetted, the gas 7that is separated from the liquid 6 will not permeate the filter 5 andcan become trapped within the filter housing 2. The gas 7 can includeair and other gases. The gas 7 can impede the liquid 6 from reachingportions of the filter 5 and can prevent the liquid 6 from being fullydistributed around the filter 5 during the filtration process. As aresult, filtration through the filter 5 can be essentially concentratedin certain portions of the filter 5, while other portions of the filter5 can remain unused. The life of the filter 5 is reduced, because thefilter 5 must be replaced when any portion of the filter becomesexpended or clogged, or the pressure drop becomes too large.

FIG. 2A illustrates a filtration device 10 according to one embodimentof the invention. The filtration device 10 can include a housing 12having a fluid inlet 14 and a liquid outlet 16. The housing 12 cansupport a filter 18. In some embodiments, the filter 18 can at leastpartly block a gas from permeating through it. The filter 18 can dividethe housing 12 into an upstream chamber 20 and a downstream chamber 22.A fluid can be supplied to the upstream chamber 20 through the fluidinlet 14. The fluid can pass through the filter 18 into the downstreamchamber 22. In some embodiments, the filter 18 can be porous andconstructed of a suitable material or combination of materials. In otherembodiments, the filter 18 can be non-porous and constructed of asuitable material or combination of materials. The liquid outlet 16 canbe coupled to the housing 12 to receive the filtered fluid from thedownstream chamber 22. The liquid outlet 16 can be coupled to otherdevices or can supply the filtered fluid directly to an end usage point.

In some embodiments, the housing 12 can further include a gas outlet 24.The gas outlet 24 can be in fluid communication with the upstreamchamber 20. The gas outlet 24 can include a membrane 26 configured topermit a gas to pass through it but not the fluid. In some embodiments,the membrane 26 can be porous, hydrophobic, and/or oleophobic. Themembrane 26 can be made from polymers, such as Teflon (PTFE),polypropylene, polyethylene, and other suitable materials. In otherembodiments, the membrane 26 can be non-porous and can be constructed ofa suitable material or combination of materials. In one embodiment, themembrane 26 can be made from a thermoset polymer. In some embodiments,the membrane 26 can include two or more layers of different or similarcharacteristics, including a support layer 28 to provide the membrane 26with suitable rigidity. The membrane 26 can further include additionalmembranes and/or support layers, including porous, microporous andnon-porous layers. While the above embodiment defines the chamber 20 asthe upstream side of the filter 18 and being in fluid communication withthe fluid inlet 14 and defines the chamber 22 being the downstream sideof the filter 18 and in fluid communication with the liquid outlet 16,this does not have to be so. In some embodiments, the direction ofliquid flow may be from the chamber 22 through the membrane 18 to thechamber 20, where the chamber 22 would then be the upstream side and bein fluid communication with the fluid inlet 14 and the gas outlet 24.

In some embodiments, a gas entrained in the fluid entering the housing12 through the fluid inlet 14 can be separated from the fluid, forexample by the filter 18. In some embodiments, the upstream chamber 20can be designed to collect the gas at the gas outlet 24. The gas canpass through the membrane 26 and can be released or “vented” to theoutside ambient environment. In some embodiments, the membrane 26 can bepart of the housing 12. In some embodiments, the membrane 26 can atleast partially define the upstream chamber 20. The membrane 26 canprevent the gas from interfering with the filtration process. As aresult, substantially the entire filter 18 can be more uniformly used bythe fluid.

FIG. 2B illustrates a filtration device 100 according to anotherembodiment of the invention. The filtration device 100 can be similar tothe filtration device 10. The filtration device 100 can include ahousing 112 having a fluid inlet 114 and a liquid outlet 116. Thehousing 112 can support a filter 118. The filter 118 can divide thehousing 112 in an upstream chamber 120 and a downstream chamber 122. Afluid can be supplied to the upstream chamber 120 through the fluidinlet 114. The fluid can pass through the filter 118 into the downstreamchamber 122. In some embodiments, the filter 118 can be porous andconstructed of a suitable material or combination of materials. In otherembodiments, the filter 118 can be non-porous and constructed of asuitable material or combination of materials. The liquid outlet 116 canbe coupled to the housing 112 to receive the filtered fluid from thedownstream chamber 122 and to direct the filtered fluid from thefiltration device 100.

In some embodiments, the housing 112 can further include a gas outlet124. The gas outlet 124 can be in fluid communication with the upstreamchamber 120. The gas outlet 124 can include a membrane 126 configured topermit a gas to pass through it but not the fluid. The membrane 126 caninclude two or more layers of different or similar characteristics,including a support layer 128 to provide the membrane 126 with suitablerigidity. In some embodiments, the membrane 126 can be substantiallysimilar to the membrane 26.

In some embodiments, a gas entrained in the fluid entering the housing112 through the fluid inlet 114 can be separated from the fluid, forexample by the filter 118. In some embodiments, the upstream chamber 120can be designed to collect the gas at the gas outlet 124. The gas canpass through the membrane 126 and can be released to the liquid outlet116 and/or the downstream chamber 122. The membrane 126 can help preventthe gas from interfering with the filtration process. As a result,substantially the entire filter 118 can be used more uniformly by thefluid.

In some embodiments, the filtration device 100 can be used if none ofthe gas can be released to the ambient environment, for example, if thegas is hazardous and/or otherwise violates local, state, and federalcodes. In other embodiments, the filtration device 100 can be used if anobjective of the filtration application is to remove particulate fromthe fluid without removing entrained gases. The filter 118 can separatethe entrained gas from the fluid. The gas can be collected by the gasoutlet 124. The membrane 126 can allow the gas to rejoin the fluiddownstream of the filter 118 so that the filter 118 only removesparticulate without removing substantially any gases. In someembodiments, the filtration device 100 can be used to filter carbonatedwater.

FIGS. 3A and 3B illustrate a venting system 200 including a membrane202. The venting system 200 can include a fluid inlet 204, a liquidoutlet 206, and a gas outlet 208. The membrane 202 can separate anentrained gas from a fluid entering the venting system 200 through thefluid inlet 204. The gas can be dissolved or otherwise entrapped in thefluid. The membrane 202 can help prevent the liquid from reaching thegas outlet 208.

As shown in FIG. 3A, the venting system 200 can include a housing 210.The housing 210 can include the fluid inlet 204, the liquid outlet 206,and the gas outlet 208. The housing 210 can enclose the membrane 202. Insome embodiments, the membrane 202 can be substantially planar. As shownin FIG. 3B, the venting system 200 can be symmetric to an axis and/or aplane 212. In some embodiments, the membrane 202 can be circular or caninclude at least two opposing membranes 202. In some embodiments, themembrane 202 can include a support layer 214, which can be sufficientlystrong to support the membrane 202 without the presence of the housing210, in some embodiments.

FIG. 4A illustrates a venting system 300 according to one embodiment ofthe invention. The venting system 300 can include a housing 302, a fluidinlet 304, and a liquid outlet 306. The housing 302 can include an uppercavity or reservoir 308. In some embodiments, the reservoir 308 can beimpermeable on all sides except for an upper portion 310. The upperportion 310 can include a gas outlet 312 and a membrane 314. In someembodiments, the membrane 314 can be positioned at any suitable locationwithin the reservoir 308. In some embodiments, the membrane 314 can atleast partly define the reservoir 308. The membrane 314 can besubstantially similar to the membrane 26, the membrane 126, and/or themembrane 202.

In operation, a fluid can enter the reservoir 308 through the fluidinlet 304 and can exit through the liquid outlet 306. While passingthrough the housing 302 and/or the reservoir 308, a gas entrained in thefluid can be collected within the reservoir 308. The gas within thereservoir 308 can remain in contact with the membrane 314 untilpermeating through it to the gas outlet 312, which can be of a suitablesize.

In some embodiments, the reservoir 308 can help the gas separate fromthe fluid. The time the fluid can remain in the reservoir 308 can bedetermined by the size of the reservoir 308. The reservoir 308 cansubstantially prevent the gas from reaching the liquid outlet 306,thereby ensuring that the gas can accumulate at the membrane 314. Insome embodiments, the time the gas can be in contact with the membrane314 before permeating through it, can be substantially longer than aflow-through time of the fluid through the venting system 300. In someembodiments, the membrane 314 can be non-porous. In some embodiments,the membrane 314 can include thermoset polymers.

While porous membranes have been used for venting a gas from a liquidstream, this proves inadequate for many venting applications. If theliquid being vented is a complex liquid containing low surface tensioncomponents, or surfactants, the pores of a porous membrane will becomewetted, and the liquid will flow through. Likewise, if the device isused for a long period of time, even with simple high surface tensionliquids, temperature fluctuations may cause evaporation and condensationwithin the pores of the membrane, causing wetting, and eventual liquidflow through. Using a non-porous material for the membrane 314 meansthat the membrane 314 can never become wetted, even over long periods oftime and with complex liquids. Using a non-porous material for themembrane 314 means that the device can be constructed with a largereservoir 308 to hold the separated gas until it permeates through themembrane 314, since non-porous membranes will have a much lower gastransmission rate. Likewise, the venting system 300 can be constructedwith significantly more area for the membrane 314 to accommodate thelower gas transmission rate.

FIG. 4B illustrates the venting system 300 including a baffle 316according to one embodiment of the invention. The baffle 316 canprotrude into the reservoir 308. The baffle 316 can create a tortuousflow path allowing centrifugal forces and/or buoyancy forces to act onthe fluid. The baffle 316 can include a lower end 318 and an upper end320.

The baffle 316 can have a suitable geometrical shape, includingrectangular and cylindrical shapes. In some embodiments, the baffle 316can be coupled to at least two sides of the reservoir 308 so that thefluid entering the venting system 300 can be forced to flow over theupper end 320 before exiting the venting system 300 through the liquidoutlet 306. As a result, the minimum fluid flow-through time can beprolonged, even though the average flow-through time remains unchanged.The longer fluid retention within the housing 302 can increase thelikelihood of the entrained gas being released within the reservoir 308and eventually permeating through the membrane 314. Other configurationsforming tortuous flow paths can be used rather than the baffle 316.

FIG. 4C illustrates the venting system 300 including three baffles 316according to one embodiment of the invention. A first baffle 322 can becoupled to a bottom of the reservoir 308. In some embodiments, the lowerend 318 of the first baffle 322 can promote fluid flow along the firstbaffle 322. In one embodiment, the lower end 318 of the first baffle 322can be curved. The first baffle 322 and a portion of the housing 302 canform a channel 324. In some embodiments, a distance from the upper end320 of the first baffle 322 to the membrane 314 can be substantiallylarger than the width of the channel 324. As a result, the collected gascan remain in contact with the membrane 314 until permeated therethroughsubstantially without interfering with the flow rate of the fluidthrough the venting system 300.

In some embodiments, a second baffle 326 can be coupled to the upperportion 310 of the reservoir 308. In some embodiments, a supportstructure (e.g., a beam) can couple the end 318 of the second baffle 326to the upper portion 310. In some embodiments, the end 318 of the secondbaffle 326 can be adjacent to the membrane 314. The end 320 of thesecond baffle 326 can be directed toward the bottom of the reservoir308. The baffles 316 can be the same length or different lengths. Theend 318 of the second baffle 326 can be designed to help trap theseparated gas in the vicinity of the membrane 314. As a result, the timethe gas has to permeate the membrane 314 can be increased. In someembodiments, a distance between the end 320 of the second baffle 326 andthe bottom of the reservoir 308 can be related to the width of thechannel 324. In some embodiments, a third baffle 328 can have the samelength or a different length than the first baffle 322 and/or the secondbaffle 326.

FIG. 5A illustrates a venting system 400 according to another embodimentof the invention. The venting system 400 can include a housing 402, afluid inlet 404, a liquid outlet 406, and a reservoir 408. In someembodiments, the reservoir 408 can be impermeable on all sides exceptfor an upper portion 410. The upper portion 410 can include a gas outlet412 and a membrane 414. The membrane 414 can be substantially similar tothe membrane 314. In some embodiments, the membrane 414 can benon-porous.

In some embodiments, the fluid inlet 404 can be in fluid communicationwith a weir 416. In other embodiments, the fluid inlet 404 can protrudeinto the reservoir 408 integrally forming the weir 416. The weir 416 canbe elongated in shape and can have a cross section that is quadratic,rectangular, hexagonal, circular, oval, or another suitable geometricshape. In some embodiments, the cross section of weir 416 can complementa cross section of the housing 402. In other embodiments, thecross-sectional shape of the weir 416 and the housing 402 can bedifferent. The weir 416 can include a lower end 418 and an upper end420. In some embodiments, a cross-sectional area of the lower end 418can be substantially equal to a cross-sectional area of the upper end420. In some embodiments, the fluid inlet 404 can be fluidly connectedto the lower end 418.

A fluid entering the housing 402 through the fluid inlet 404 can bedirected to the weir 416. In some embodiments, the flow direction of thefluid within the weir 416 can be against gravity. The fluid can reachthe upper end 420 and can overflow from the weir 416 into the reservoir408. In some embodiments, the fluid can be released from the weir 416into the reservoir 408 before exiting through the liquid outlet 406.Entrained gas released from the fluid can contact the membrane 414 andcan eventually permeate to the gas outlet 412.

FIG. 5B illustrates a venting system 500 according to another embodimentof the invention. The venting system 500 can include a housing 502, afluid inlet 504, a liquid outlet 506, and a reservoir 508. In someembodiments, the reservoir 508 can be impermeable on all sides exceptfor an upper portion 510. The upper portion 510 can include a gas outlet512 and a membrane 514. The venting system 500 can be similar to theventing system 400, and the membrane 514 can be substantially similar tothe membrane 414. In some embodiments, the membrane 514 can benon-porous.

In some embodiments, the venting system 500 can include a weir 516having a lower end 518 and an upper end 520. The fluid inlet 504 can befluidly coupled to the lower end 518. In some embodiments, the lower end518 can have a smaller cross-sectional area than the upper end 520. As aresult, the fluid entering the weir 516 through the inlet 504 can bedecelerated while flowing through the weir 516. In some embodiments, theweir 516 can be substantially conical. In some embodiments, the weir 516can increase a flow-through time of the fluid in order to enhance a gasseparation from the fluid. Entrapped gas can have more time to coalesceand can be collected by the membrane 514. In some embodiments, avertical velocity of the fluid flowing through the weir 516 can beslower than a velocity of the separated gas. In some embodiments, thefluid entering the weir 516 can rise to the upper end 520. In otherembodiments, the fluid entering the weir 516 can swirl.

In some embodiments, the ratio of cross-sectional areas of the upper end520 to the lower end 520 can be adjusted according to the properties ofthe fluid and flow rate. For example, if the venting system 500 is usedto extract air from food products, such as syrup or ketchup, the ratioof the cross-sectional areas of the upper end 520 to the lower end 518can be higher than the ratio of the cross-sectional areas of the upperend 520 to the lower end 518 for aqueous fluid streams.

FIGS. 5C and 5D illustrate the venting system 500 according to otherembodiments of the invention. The weir 516 can include a substantiallystraight portion 522, a gradually expanding portion 524, and an outersurface 526. In some embodiments, the gradually expanding portion 524can act as a diffuser. In some embodiments, the outer surface 526 can besubstantially straight. In other embodiments, the outer surface 526 cancorrespond to a shape of the reservoir 508. The outer surface 526 canhelp direct fluid flow toward the liquid outlet 506. In someembodiments, the fluid entering the venting system 500 can overflow theweir 516 and can be guided to the liquid outlet 506 by the outer surface526.

As shown in FIG. 5C, the straight portion 522 can be positioned upstreamof the gradually expanding portion 524. In some embodiments, across-sectional area of the straight portion 522 can be substantiallyequal to the smallest cross-sectional area of the gradually expandingportion 524. In one embodiment, the transition from the substantiallystraight portion 522 to the gradually expanding portion 524 can besmooth. Alternatively, as shown in FIG. 5D, the gradually expandingportion 524 can be positioned upstream of the substantially straightportion 522. In some embodiments, the cross-sectional area of thestraight portion 522 can be substantially equal to the largestcross-sectional area of the gradually expanding portion 524. In someembodiments, the weir 516 can include a converging portion and/or arapid change in cross-sectional area, such as one or more steps (notshown).

FIG. 6A illustrates a venting system 600 according to one embodiment ofthe invention. The venting system 600 can include a housing 602, a fluidinlet 604, a liquid outlet 606, and a reservoir 608. The housing 602 canenclose the reservoir 608. The housing 602 can include an upper portion610 having a gas outlet 612. The housing 602 can be impermeable to thefluid flowing through the venting system 600 except at the gas outlet612. A membrane 614 can be positioned within the reservoir 608. Themembrane 614 can be adjacent to the gas outlet 612. The fluid enteringthe venting system 600 can come into contact with the membrane 614. Themembrane 614 can be substantially similar to the membrane 514. In someembodiments, the membrane 614 can allow a gas entrapped within the fluidto permeate through to the gas outlet 612, while substantiallypreventing other components of the fluid from reaching the gas outlet612.

As shown in FIG. 6A, the venting system 600 can include a weir 616having a lower end 618 and an upper end 620. The weir 616 can furtherinclude an inner surface 624 and an outer surface 626. In someembodiments, the inner surface 624 can be curved between the lower end618 and the upper end 620. The inner surface 624 can include convexcurvature and/or concave curvature. In some embodiments, across-sectional area of the lower end 618 can be smaller than across-sectional area of the upper end 620. In some embodiments, theinner surface 624 can form a diffuser. In some embodiments, the innersurface 624 can be flared. In some embodiments, the inner surface 624can be shaped similar to a trumpet funnel. In some embodiments, theouter surface 626 can be conical.

FIG. 6B illustrates the venting system 600 according to anotherembodiment of the invention. The weir 616 can include the inner surface624 and the outer surface 626. The outer surface 626 can be curvedbetween the lower end 618 and the upper end 620. In some embodiments,the thickness of the weir 616 can vary between the lower end 618 and theupper end 620 (e.g., the weir 616 can have a petal shape as shown inFIG. 6B). In some embodiments, the upper end 620 can be designed to helpprevent a fluid separation region when the fluid is flowing over theweir 616.

The reservoir 608 can include an inner wall 628. As shown in FIG. 6B,the inner wall 628 can be curved. In some embodiments, the curvature ofthe inner wall 628 can complement the curvature of the outer surface 626of the weir 616. In some embodiments, the inner wall 628 can help directfluid flow toward the liquid outlet 606. In some embodiments, the liquidoutlet 606 can be fluidly coupled to the reservoir 608 at the lowestpoint of the reservoir 608. In some embodiments, the liquid outlet 606can be positioned adjacent the fluid inlet 604. In some embodiments, theweir 616 can be centrally positioned within the reservoir 608. In otherembodiments, the liquid outlet 606 can be centrally positioned withinthe reservoir 608 and the weir 616 can be positioned off to one side ofthe liquid outlet 606.

FIG. 7 illustrates a venting system 700 according to one embodiment ofthe invention. The venting system can include a housing 702 having afluid inlet 704 and a liquid outlet 706. A lid 708 can be coupled to thehousing 702 using screws 710. In some embodiments, the screws 710 can beevenly distributed along an outer perimeter of the lid 708. In someembodiments, the lid 708 can include one or more gas outlets 712.

FIG. 8 further illustrates internal components of the venting system 700according to one embodiment of the invention. The venting system 700 caninclude a membrane 714, a support layer 716, and a weir 718. The housing702 can include a groove 720 that engages with the lid 708. In someembodiments, the lid 708 can also engage the membrane 714 and/or thesupport layer 716 with the groove 720. In some embodiments, the groove720 can form a pinch seal.

The weir 718 can be positioned in a reservoir 722 of the housing 702. Insome embodiments, the housing 702 can include an inner wall 724, whichcan enclose the reservoir 722. The fluid inlet 704 and the liquid outlet706 can be in fluid communication with the reservoir 722.

FIG. 9 further illustrates the interior of the housing 702. The housing702 can include a first expansion chamber 726. The inner wall 724 caninclude a lower end 728 and an upper end 730. The inner wall 724 can becurved. The inner wall 724 can be curved adjacent to the lower end 728and can be substantially straight adjacent to the upper end 730. Thegroove 720 can be positioned adjacent to the upper end 730. The firstexpansion chamber 726 can be positioned adjacent to the lower end 728.The first expansion chamber 726 can be in fluid communication with thefluid inlet 704 and the reservoir 722. The first expansion chamber 726can be centrally positioned with respect to the reservoir 722. Anaperture 732 can enable fluid communication between the reservoir 722and the liquid outlet 706. The aperture 732 can be located near thebottom end 728. The aperture 732 can be positioned adjacent to the firstexpansion chamber 726.

FIG. 10 illustrates the weir 718 positioned in the housing 702. The weir718 can be in fluid communication with the fluid inlet 704. The weir 718can include an inner surface 734 and an outer surface 736. The innersurface 734 and/or the outer surface 736 can be curved. The weir 718 canbe centrally positioned in the reservoir 722. The aperture 732 can bepositioned adjacent to the outer surface 736. The fluid entering theweir 718 through the fluid inlet 704 can overflow the weir 718 into thereservoir 722. The inner wall 724 and/or the outer surface 736 can helpdirect the fluid in the reservoir 722 toward the aperture 732 and intothe liquid outlet 706.

FIG. 11 is a cross-sectional view of the weir 718. The weir 718 caninclude the inner surface 734, the outer surface 736, a lower end 738,and an upper end 740. The inner surface 734 can enclose a channel 742,which can include a first section 744 and a second section 746. In someembodiments, the first section 744 can be positioned adjacent to thelower end 738, and the second section 746 can be positioned adjacent tothe upper end 740. In some embodiments, the first section 744 caninclude a cylindrical shape, while in other embodiments, the firstsection 744 can include a conical shape. In some embodiments, the secondsection 746 can be curved. In one embodiment, the second section 746 canbe a diffuser.

As shown in FIG. 11, the weir 718 can include an inflow 748, an outflow750, and a passageway 752. As shown in FIG. 12, the inflow 748 can be influid communication with the fluid inlet 704 and the channel 742. Theoutflow 750 can be in fluid communication with the channel 742 and thereservoir 722. The passageway 752 can enable fluid communication of thechannel 742 with the first expansion chamber 726. In some embodiments,the inflow 748 and/or the passageway 752 can be positioned adjacent tothe lower end 738 of the weir 718 while the second section 746 of theweir 718 can be positioned at the upper end 740. In some embodiments,the inflow 748 can be substantially perpendicular to the channel 742and/or the passageway 752.

FIG. 12 is a velocity vector plot illustrating a flow path through theventing system 700 as shown in FIGS. 7-11. A first conduit 754 can be influid communication with the fluid inlet 704. The first conduit 754 canhave a larger cross-sectional area than the fluid inlet 704. The fluidinlet 704 can enable fluid communication between the first conduit 754and the lower end 738 of the weir 718. A second conduit 756 can becoupled to the liquid outlet 706. In some embodiments, the liquid outlet706 can include a second expansion chamber 758.

In some embodiments, the upper end 740 of the weir 718 can be positioneda distance D away from the membrane 714. In some embodiments, a shape ofthe weir 718 and/or the distance D can support an even flow distributionalong the membrane 714, as indicated by velocity vectors 760. The weir718 can help provide a balanced wetting of the membrane 714. The fluidflow along the weir 718 and across the membrane 714 can be substantiallysymmetric to an axis 762. The fluid flow through the venting system 700can be substantially laminar. The weir 716 can help reduce the number ofvortices 764 within the fluid flow. In some embodiments, only a singlering vortex 764 in the vicinity of the upper end 740 is generallypresent in the reservoir 722. The distance D can be chosen in accordancewith a size of the vortex 764. In some embodiments, the inner surface734, the outer surface 736, and/or the inner wall 724 can be designed tohelp provide optimized gas separation from the fluid and/or an increaseflow rate of the separated gas toward the membrane 714.

In some embodiments, the venting system 700 can include a “first-in,first-out” (FIFO) flow configuration. The weir 718 can be designed insuch a way that fluid particles entering the venting system 700 throughthe fluid inlet 704 can reach the liquid outlet 706 before subsequentfluid particles can reach the liquid outlet 706. Fluid particles alreadylocated within the venting system 700 can exit the venting system 700before the fluid particles reach the liquid outlet 706. In someembodiments, a first fluid can be supplied to the venting system 700 fora first period of time. After the first period of time has elapsed, asecond fluid can be supplied to the venting system 700 for a secondperiod of time. The FIFO flow configuration can eliminate the necessityto flush the venting system 700 before the second fluid is supplied. Forexample, if the venting system 700 is used to separate air from a syrupused in a fountain drink dispenser, the venting system 700 can allowswitching of flavors of the syrup. If a first syrup supplied to theventing system 700 is to be switched to a second syrup (e.g., forpromotions, flavor of the month, market trends, etc.), the second syrupcan substantially push out the first syrup from the venting system 700.A transition time before only traces of the first syrup can be detectedin the second syrup can be minimized without having to flush the ventingsystem 700.

In applications involving viscous fluids, such as syrup, ketchup, andother food products, some embodiments of the invention can provideefficient separation and/or ventilation of a gas extracted from theviscous fluids without substantially affecting the efficiency of themembrane 202, 314, 414, 514, 614, 714 over prolonged periods of time. Insome embodiments, pumps, vacuums, and/or other measures may not benecessary to separate the gas from the fluid.

In some embodiments, the venting system 200, 300, 400, 500, 600, 700 canbe used in liquid supply systems. The liquid supply systems can include,for example, mixing systems and food processing systems. The ventingsystem 200, 300, 400, 500, 600, 700 can be used to remove gases from afluid before entering the liquid supply system. For example, if thefluid is a viscous food product, like ketchup, honey, and molasses,entrapped air can cause the viscous food product to splatter whendispensed. The venting system 200, 300, 400, 500, 600, 700 cansubstantially remove the entrapped air and can prevent the viscous foodproduct from splattering. As a result, the venting system 200, 300, 400,500, 600, 700 not only ensures delivery of precise quantities of theviscous food product, but also reduces the need to clean splattered foodproduct. In some embodiments, the venting system 200, 300, 400, 500,600, 700 can reduce the risk of damage to the liquid supply systemcaused by entrapped gas. For example, if the viscous food product isbeing pumped, entrapped air can cause sudden accelerations anddecelerations within the pump, increasing mechanical stress on the pump.

Certain kinds of fluids are often transported in “bag-in-box” (BIB)units. According to some embodiments, the BIB unit can include a plasticbag enclosed by a cardboard box. The plastic bag, when holding thefluid, can easily deform. To give the plastic bag structural integrity,the cardboard box can prevent the plastic bag from deforming beyond anintended shape. Typically, liquids and air are mixed inside the plasticbag. When the plastic bag moves with respect to the cardboard box, anincreased amount of air can get entrapped within the liquid inside theBIB unit. The venting system 200, 300, 400, 500, 600, 700 can besuitable for removing the increased amount of entrapped air from thefluid of the BIB unit. In some embodiments, the venting system 200, 300,400, 500, 600, 700 can help ensure the delivery of accurate flowquantities from the BIB unit. For example, if a BIB unit holding a syrupis coupled to a fountain drink dispenser, the venting system 200, 300,400, 500, 600, 700 can help ensure that substantially equal amounts ofsyrup are being dispensed for each drink. As a result, the ventingsystem 200, 300, 400, 500, 600, 700 can help ensure that one drinktastes the same as the next.

In some embodiments, the venting system 200, 300, 400, 500, 600, 700 canbe used to extract a gas from mineral oils, synthetic oils, and/or otherhydrocarbons. In some embodiments, the venting system 200, 300, 400,500, 600, 700 can be used to remove entrapped air from motor oils, gearoils, and automatic transmission fluids. The motor oils, gear oils, andtransmission fluids can be transported to service facilities incontainers and/or BIB units. In order to avoid spillage when the motoroils, gear oils, and automatic transmission fluids are being handled,the containers are not generally completely filled, allowing air to gettrapped within those fluids. These fluids may also be transported in BIBunits, with the same entrapped air issues as liquid food products. Theentrapped air can result in erroneous flow quantity readings when themotor oils, gear oils, and automatic transmission fluids are beingdispensed. The resulting uncertainty of a correct fill level can resultin a technician having to check the fluid level and, possibly, top-offthe motor oils, gear oils, and automatic transmission fluids until thecorrect fill level is reached. The venting systems 200, 300, 400, 500,600, 700 can reduce the air content of the motor oils, gear oils, andautomatic transmission fluids, eliminating the need to correct the filllevels.

In some embodiments of the invention, plug flow-like characteristics(e.g., a cross-sectional flow profile of close to a uniform velocitydistribution) can be achieved. Other configurations can be employed toeffectively reduce fluid jets, vortices, dead regions and/or otherwisefacilitate the separation of entrapped gas from the fluid and/or theventilation of the separated gas from the venting systems 200, 300, 400,500, 600, and 700.

The term “non-porous” as used herein and in the appended claim generallyrefers to a material which may be free of pores or voids, or may havepores or voids that are not in fluid communication from one side of themembrane 26, 126, 202, 314, 414, 514, 614, 714 to the other, and whichis a barrier to convective flow of liquids or gases. While a materialsuch as the material used in construction of the membrane 26, 126, 202,314, 414, 514, 614, 714 according to some embodiments of the inventionmay be non-porous, it may still be “permeable” to liquids or gases. Theterm “permeable” (and conversely “impermeable”) as used herein and inthe appended claims generally describes the property of a material toallow a particular species, such as a gas or a liquid, to transporttherethrough (or conversely, impede transport therethrough). The term“permeable” generally describes the overall property of mass transfer bydiffusion at a molecular level, and in no way is any particularscientific mechanism by which this occurs implied.

In some embodiments, the membrane 26, 126, 202, 314, 414, 514, 614, 714can include two or more layers of various or similar characteristics. Insome embodiments, the membrane 26, 126, 202, 314, 414, 514, 614, 714 caninclude a support layer to provide the membrane 26, 126, 202, 314, 414,514, 614, 714 with suitable rigidity. The membrane 26, 126, 202, 314,414, 514, 614, 714 can further include independent additional membranesand/or support layers, including porous, microporous and non-porouslayers. In some embodiments, the membrane 26, 126, 202, 314, 414, 514,614, 714 can include a combination of suitable materials.

The membrane 26, 126, 202, 314, 414, 514, 614, 714 of some embodimentscan be made of a variety of materials, such as hydrophobic and/orchemically inert materials, which can be resistant to being wetted byliquids, such as low surface energy liquids, solvents, oils,surfactants, proteins, carbohydrates, or mixtures thereof. For example,the membrane 26, 126, 202, 314, 414, 514, 614, 714 can be constructed ofporous thermoplastic fluoropolymers, such astetrafluoroethylene-hexafluoropropylene copolymer (FEP),tetrafluoroethylene-(perfluoroalkyl) vinyl ether copolymer (PFA), oramorphous fluoropolymers. In some embodiments, the membrane 26, 126,202, 314, 414, 514, 614, 714 can include thermoformed films.

In some embodiments, the membrane 26, 126, 202, 314, 414, 514, 614, 714can be a thermoset polymer. The membrane 26, 126, 202, 314, 414, 514,614, 714 can include a plurality of highly cross-linked polymers. As aresult, the membrane 26, 126, 202, 314, 414, 514, 614, 714 can includemultiple, three-dimensional bonds between different polymers. In someembodiments, the thermoset polymer can result in a more rigid membrane26, 126, 202, 314, 414, 514, 614, 714, which can possibly result in areduction and/or elimination of the support layer.

The membrane 26, 126, 202, 314, 414, 514, 614, 714 can include polymericorganosilicone compounds. In some embodiments, the membrane 26, 126,202, 314, 414, 514, 614, 714 can be made from a silicone derived frompolydimethylsiloxane and/or a fluorosilicone derived fromfluorovinylmethylsilicone. The membrane 26, 126, 202, 314, 414, 514,614, 714 can include vinyl or other functionalities to alter certainproperties of the membrane 26, 126, 202, 314, 414, 514, 614, 714.

In some embodiments, the membrane 26, 126, 202, 314, 414, 514, 614, 714can be made from ethyl cellulose, polyethylene, and polypropylenematerials. In other embodiments, the membrane 26, 126, 202, 314, 414,514, 614, 714 can be made from polyimides, nitrate butadiene rubber(NBR), polyurethanes, and/or amorphous fluoropolymers. Morespecifically, the membrane 26, 126, 202, 314, 414, 514, 614, 714 of someembodiments can include polyisoprene (Natural Rubber),poly(4-methyl-1-pentene), polydimethylsiloxane, polyvinylmethylsiloxane,polyphenylvinylmethylsiloxane, polyoctenamer, and/or nitrile rubber.

Various characteristics of the membrane 26, 126, 202, 314, 414, 514,614, 714 (e.g., shape, surface area, and thickness) can influence itsproperties, such as gas permeation rate, strength, and durability. Thedesired functionality can be achieved through optimization, compromise,and/or trade-off between properties and/or materials.

It will be appreciated by those skilled in the art that while theinvention has been described above in connection with particularembodiments and examples, the invention is not necessarily so limited,and that numerous other embodiments, examples, uses, modifications anddepartures from the embodiments, examples and uses are intended to beencompassed by the claims attached hereto. The entire disclosure of eachpatent and publication cited herein is incorporated by reference, as ifeach such patent or publication were individually incorporated byreference herein. Various features and advantages of the invention areset forth in the following claims.

The invention claimed is:
 1. A passive venting system that vents gasfrom one of liquid food product and drinking water entrained with gas,the venting system comprising: a housing including a reservoir, thereservoir including a fluid inlet, a gas outlet, and a liquid outlet;and a single non-porous membrane in fluid communication with thereservoir and the gas outlet, the non-porous membrane being permeable tothe gas and substantially impermeable to the one of liquid food productand drinking water; the single non-porous membrane being positionedadjacent to an upper portion of the housing.
 2. The venting system ofclaim 1, wherein the reservoir provides a tortuous flow path for theliquid.
 3. The venting system of claim 2, wherein the reservoir includesat least one baffle to create the tortuous flow path.
 4. The ventingsystem of claim 1, wherein the non-porous membrane is coupled to thehousing with a pinch seal.
 5. The venting system of claim 1, wherein thenon-porous membrane is constructed of at least a thermoset polymer. 6.The venting system of claim 1, wherein the non-porous membrane isconstructed of at least a silicone.
 7. The venting system of claim 1,wherein at least one of the housing and the reservoir is constructed aspart of at least one of a liquid pumping system, a liquid transportsystem, and a liquid storage system.
 8. The venting system of claim 1,wherein the upper portion of the housing includes at least one outlet,and wherein the single non-porous membrane is positioned adjacent to theat least one outlet.